The present invention relates to systems and methods for suppressing low frequency noise and drift in wireless sensors.
Passive imaging sensors operating in millimeter-wave atmospheric windows can capture images through obstacles such as fog, clouds, smoke and clothing. This unique feature enables several important applications including theft prevention, low-visibility airplane-landing, concealed weapon detection, covert terrestrial and aerial surveillance, highway traffic monitoring and precision targeting. Existing electronics technologies for passive imaging are bulky, expensive and require complicated moving mechanical components to meet performance requirements. There is a clear need for novel solutions that can significantly reduce the size, weight, power dissipation and cost (SWAP-C of passive imaging sensors while improving the performance and image quality. Such light-weight, low-power solutions will lead to a paradigm shift in the state-of-the-art and will enable new non-intrusive products such as hand-held imagers for port security, helmet-mounted imagers for the warfighter and compact imagers mounted on unmanned aerial vehicles (UAVs).
State-of-the-art imagers are currently built using an array of receivers, each an assembly of several discrete compound-semiconductor (III-V) integrated circuits (ICs). In order to generate thousands of image pixels, either thousands of these receivers must be used (prohibitively heavy/expensive) or a smaller array must be scanned sequentially (requiring mechanical scanners). These receivers also require periodic mechanical/electronic switching to remove flicker noise/drift, resulting in additional components and a factor-of-two degradation in imager sensitivity. In order to address these challenges, highly-integrated imaging solutions in silicon technologies are needed. However, the performance of current passive imaging receivers in SiGe/CMOS is far from the acceptable level , due to a combination of (a) inferior transistor noise figure, (b) high insertion loss of Dicke switch, and (c) use of conventional architectures. It is clear that innovative architectures and techniques must be developed to address these issues and hence enable silicon-based receivers to meet the challenging requirements of practical imaging.